The present invention relates generally to chemical and biological sampling, and more specifically to a system for real-time monitoring of ambient air for the presence of biological and chemical compounds.
The need for accurate, real-time systems for detection of chemical and biological compounds or agents in the ambient air has increased significantly in recent years. Such devices are useful in numerous areas, such as biological and chemical warfare monitoring and testing, and monitoring of environmental air conditions.
Since the end of the Cold War and the resulting decrease in tensions between international superpowers, regional stability between nationalistic, religious, and ethnic groups has risen, leading to substantial threats to peace across the globe. At the same time, advances in chemical and biological technology have lead to an increase in the availability of chemical and biological agents worldwide. Such agents are relatively inexpensive and easy to produce, making them attractive to various terrorist and other organizations. Since the events of Sep. 11, 2001, and the subsequent anthrax attacks, public and private awareness of the need to monitor the air for biological and chemical agents and compounds has increased.
In the case of biological and chemical warfare agents, it is often imperative (such as on a battlefield, for example) that a device for immediate, real-time sampling and analysis of the ambient air is available. Further, environmental air quality must, in some non-military situations, be sampled and analyzed in real-time. For example, measuring air quality in poorly-ventilated mines requires real-time collection and analysis of samples due to the immediate threat to the health and safety of persons in the mine posed by the presence of toxic gases or other compounds.
Prior art devices, such as that described in U.S. Pat. No. 5,861,316, provide the capability for real-time sampling and analysis of ambient air. Such devices, however, have certain deficiencies that are addressed by the present invention. The prior art device in the '316 patent, for example, includes a wet-wall contactor to collect airborne particles into a liquid. Maintaining the correct fluid level in such a collector is paramount to the success of the device. Optics-based systems can be rendered inadequate by bubbles, dirt, or contaminants in the liquid. Thus, there exists a need for an ambient air sampling device that provides improved fluid level control. In addition, the prior art devices typically include contactors having an inlet slit for passage of an air stream into the contactor, wherein the sampling fluid in the contactor covers approximately 40%-50% of the inlet slit. As a result, a substantial portion of the air stream is able to enter the contactor without passing through the fluid. What is needed, therefore, is a device wherein the entire inlet slit is covered by the contact fluid, such that all of the air stream entering the contactor passes into the fluid, requiring less power to effectively sample the same amount of air as the prior art device and resulting in a lighter, more easily portable device.
The present invention addresses the above and other limitations of the prior art.